Stabilization of alkylidenebicycloheptenes



United States Patent 3,409,683 STABILIZATION OF ALKYLIDENE- BICYCLOHE I TENES Samuel B. Britton, Charleston, W. Va., assignor to Union Carbide Corporation, a corporation of New York No Drawing. Filed June 7, 1967, Ser. No. 644,084

9 Claims. (Cl. 260-6665) This invention relates to new compositions of matter and an alkylcatechol, a hydroquinone, or a monoalkyl ether of hydroquinone.

The -alkylidenebicyclo[2.2.1]hept-2-enes of the general formula:

divalent alkylidene radical containing R is hydrogen wherein R is the from 2 to about 3,151,173 together These compounds find use as termonomers in the production of elastomers with ethylene and propylene. Illustrative of the 5-alkylidenebicyclo[2.2.1]hept-2-enes one can mention 5 ethylidenebicyclo[2.2.1Jhept 2 ene, 5- ethylidene-G-ethylbicyclo[2.2.1]hept-2-ene, 5 ethylidene- 6 decylbicyclo[2.2.1]hept 2 --ene, 5-propylidenebicyclo [2.2.1]hept-2-ene, 5 butylidenebicyclo[2.2.1]hept-2-ene, -butylidene-6-methylbicyclo[2.2.1]hept-2-ene, 5 decylidenebicyclo[2.2.1Jhept-Z-ene, and the like.

However, on storage the alkylidenebicycloheptenes form a polymeric gum, particularly in the presence of air or iron oxides, whose presence is undesired when the monomers are used for the production of terpolymer elastomers. The removal of this gum involves an expensive, time consuming procedure.

It has now been found that 5-alkylidenebicyclo[2.2.1] hept-Z-enes can be stabilized against oxidation by the incorporation therein of a small amount of a stabilizer as hereinafter defined. The amount of stabilizer required is not narrowly critical. It can be added to the alkylidenebicycloheptene in an amount of from about 50 p.p.m. to about 2,500 p.p.m. or more. The preferred concentration is from about 100 to about 500 p.p.m., with concentrations from about 100 to about 250 p.p.m. more preferred since at such concentrations the stabilizer need not be procedures of mixing and dissolving.

The stabilizers that can be used are: (i) the alkylcatechols containing from 1 to about 8 carbon atoms in the alkyl chain, such as 4-methylcatechol, 4-tertiary butylcatechol, 4-(2-ethylhexyl)catechol, 3,5-ditertiary butylcatechol, and the like; (ii) the hydroquinones containing up to about 8 carbon atoms in the alkyl chain, such as 3,409,683 Patented Nov. 5, 1968 v v 2 hydroquinone, methylhydroquinone, butylhyd'roquinone, dimethylhydroq'uinone, octylhydroquinone and the like; and the monoalkyl ethers to8 carbon atoms phenol, 2 methyl of. hydroquinone containing up in the alkyl group, such as p-methoxyp -'methoxyphenol, p butoxyphenol, p-hexoxyphenol, p-octoxyphenol and the like. The preferred stabilizer is 4-tertiary butylcatechol.

The stabilizing effect was determined by means of an gum was then weighed.

Thefollowing data shows the utility of this invention and illustrates the stabilizing effect of 4-tertiary butylcatechol at 50 C.;parts are by weight. The starting material was distilled 5-ethylidenebicyclo[2.2.l]hept-2-ene content of 0.04 Weight percent. The at the concentrations indicated and the containers were sealed and stored at 50 C.

Gum content, weight percent Stabilize concentration, p.p.m.

R 1 week 2 weeks 3 weeks 4 weeks 0-c0ntrol 0.36 0.46 0.53 0.53

ene was stabilized with p.p.m. of the stabilizers indiminutes three times per day, recapped and shaken. The containers were maintained at 50 C.

Gum content, weight percent Stabilizer 1 week 2 weeks 3 weeks 4 weeks None di-t-butyl-p-cresol Tertiary butylcatecho Ditertiary butyleatechoL.

Gum content, weight percent 14 days Stabilizer 5 days 9 days Tertiary butylcatechol.

ydroquinone... p-Methoxyphenol Some other conventional stabilizers were tried and discarded because they caused color development in the alkylidenebicycloheptene; these included phenothiazine, n-butyl-p-arninophenol and N,N'-di-sec.butyl-p-phenylene diamine.

What is claimed isz 1. A composition of matter comprising an alkylidenefined and the alkylidenebicycloheptene is5-ethy1idenebicyclo[2.2.1']hept-2-ene. 3. A composition of matter as claimed in claim 1, wherein the stabilizer is a hydroquinone as therein defined and the alkylidenebicycloheptene is S-ethylidenebicycl[2.2.1]hept2-ene. m 1

4. A composition of matter as .claimed in claim 1, wherein the stabilizer is a monoalkyl ether of hydroquinone as therein defined and the alkylidenebicycloheptene is 5-ethylidenebicyclo[2.2.1]hept2-ene. v

5. A composition of matter as claimed in claim 1, wherein the concentration of stabilizer is from about 50 p.p.m. to about 2,500 p.p.-m. by weight.

6. A composition of matter as claimed inclaim 2,

wherein the concentration of stabilizer is from about 100 ppm. to about 500 ppm. by weight.

7. A composition of matter as claimed in claim 2, wherein the stabilizer is 4-tertiary butylcatechol and it is present at a concentration offrom about p.p.m. to about 250p.p.m. H I

8. A composition of matter as' claimed in claim 3, wherein 'th e stabilizer is hydroqu'inone and it ispresent at a concentration of from 'abo'ut 100fp.p.m. to about 250 p.p.m. r A i 9. A composition of matter as claimed in claim 4 wherein the stabilizer is p-methoxyphenol and it is present at a concentration of from about 100 ppm. to about i 250 p.p. m.

References Cited UNITED STATES PATENTS 2,402,113 6/1946 Hatch et al 260-6665 2,557,684 6/1951 Powers 260-6665 X 2,561,915 7/1951" Erickson 260-6665 X 2,679,459 5/1954 Rosenwald 260-6665 X 2,831,817 4/ 1958 Ecke et al. 260-6665 X 2,561,916 7/1951 Erickson 260-6665 X DELBERT E. GANTZ, Primary Examiner.

G. E. SCHMITKON S, Assistant Examiner. 

